You may find the warmth and buoyancy of the water soothing and relaxing. Your pain level may even come down. But even if it doesn't, it won't get worse. In the meantime you can be preparing for major surgery by strengthening muscles. You'll also be improving your overall health and fitness.
Patients who show themselves committed to an exercise program before surgery are more likely to have a successful outcome afterwards. This may be because exercise improves health AND mood. It may also show your doctor which patients are truly committed to their own recovery.